2Physical Characteristics of Blood Heavier, thicker, and 3-4 X more viscous than water38o C (100.4oF)pH : 7.35 – 7.454-6 liters in an adultVaries with electrolyte concentration and amount of adipose tissue
3Blood Volume Blood volume is about 8% of body weight. 1 kg of blood ≈ 1 L of blood70 kg X 0.08 = 5.6 Kg = 5.6 L45 % is formed elements55% plasma
5Plasma 92 % Water 8% Solutes – organic and inorganic Plasma proteins – largest proportion of solutesAlbumins – 58 % of the proteins – maintain osmotic (oncotic) pressure – hold water in the bloodGlobulins – 38 % - antibodies synthesized by plasma cellsClotting factors – fibrinogen – 4 %
6Other components of plasma NutrientsHormonesElectrolytesWaste productsDissolved gases
7Formed elements Three types: Erythrocytes – red blood cells- RBC’s Leukocytes – white blood cells – WBC’sThrombocytes – platelets – cell fragments
8Hemopoiesis (Hematopoiesis) All blood cells common from a common stem cell – HemocytoblastThese are in the bone marrow (red) and develop into blood cells as needed by the bodyMitosis is signaled by biochemicals released from the body →Stem cell is signaled to differentiate into the needed type of blood cellHematopoiesis / cell breakdown continue through life.
10Erythrocytes (RBC’s) Most abundant blood cell type Transport gases Shape is importantLarge surface to volume ratioReversible deformability – can change shapeDevelopment is called erythopoiesisErythropoietin is a hormone produced by the kidneys in response to low blood oxygen levels; signals bone marrow to increase RBC production
12Cytoplasm is mostly hemoglobin (lacks organelles) Made up of 4 peptide chains that form the globin portion and four molecules of the pigment heme which contains an atom of ironOxygen binds to iron in heme (also CO)23 % of CO2 is bound to globin portionIf there is a problem with any part of the molecule it may not be functional.
14RBC breakdownHealthy RBC’s live about 120 days; we break down about 174 million per minuteRBC’s are removed from circulation by the liver and spleenBroken down into heme and globin portionsGlobin is broken down into amino acidsIron is removed from heme and stored or recycledHeme is broken down into biliverdin and then into bilirubin
19Classification of Anemias Identified by their causes or by the changes that affect the size, shape or substance of the erythrocyteTerms that end with –cytic refer to cell size, and those that end in –chromic refer to hemoglobin content.Additional terms:Anisocytosis – various sizesPoikilocytosis – various shapes
20Macrocytic / Megaloblastic Anemia Characterized by abnormally large stem cells (megaloblasts) in the marrow that mature into erythrocytes that are unusually large in size, thickness and volume. The hemoglobin content is normal, so these are normochromic anemias.
21These anemias are the result of: Ineffective DNA synthesisCommonly due to folate and B12 (cobalamin) deficiencies – malabsorption or malnutritionThese cells die prematurely, decreasing the numbers of RBC’s in circulationDNA synthesis is blocked or delayed, but RNA replication and protein synthesis are normal.
22Pernicious Anemia Common megaloblastic anemia Caused by a Vitamin B12 deficiencyPernicious means highly injurious or destructive – this condition was once fatal
23Can be congenital – baby born with a deficiency in a protein , intrinsic factor, necessary to absorb B12 from the stomachAdult onset – one example is an autoimmune dysfunction - type A chronic atrophic gastritis – where there is destruction of the gastric mucosaMost commonly affects people over 30Females are more prone to PA , and black females have an earlier onset.
24Pernicious Anemia is also associated with: Heavy alcohol consumptionHot teaCigarette smokingOther autoimmune conditionsComplete or partial removal of the stomach can cause intrinsic factor deficiency
25Develops slowly – over 20 - 30 years Usually severe by the time individual seeks treatmentEarly symptoms ignored because they are nonspecific and vague- infections, mood swings, and gastrointestinal, cardiac or kidney ailments.Usually a degree of neuropathy occursUntreated, it is fatal, us. due to heart failure
26Folate deficiency anemias Folic acid also needed for DNA synthesisDemands are increased in pregnant and lactating femalesAbsorbed from small intestine and does not require any other elements for absorption.Folate deficiency is more common than B12 deficiency
27Folate deficiency is more common than B12 deficiency , esp Folate deficiency is more common than B12 deficiency , esp. in alcoholics and those who are malnourished because of fad diets or diets low in vegetables.Estimated that 10 % of North Americans are folate deficient.Specific manifestations include cheilosis, (scales and fissures of the mouth), inflammation of the mouth, and ulceration of the buccal mucosa and tongue.
28Microcytic – Hypochromic Anemias Characterized by abnormally small RBC’s that contain reduced amounts of hemoglobin.Possible causes:Disorders of iron metabolismDisorders of porphyrin and heme synthesisDisorders of globin synthesis
29Iron Deficiency Anemia Most common type of anemia throughout the world.High risk:Individuals living in povertyFemales of childbearing ageChildrenCommon causesInsufficient iron intakeChronic blood loss – even 2- 4 ml/ dayIn men –gastrointestinal bleedingIn women – profuse menstruation, pregnancy
30Other causes: Use of medications that cause GI bleeding Surgical procedures that decrease stomach acidity, intestinal transit time, and absorptionEating disorders such as pica
31Clinical manifestations: Early symptoms are nonspecificLater - changes in epithelial tissue:Fingernails become brittle and concave (koilonychia)Tongue papillae atrophy and cause soreness, redness and burningCorners of mouth become dry and soreDifficulty in swallowing due to web of mucus and inflammatory cells at opening of esophagus
35Sideroblastic AnemiaDue to inefficient iron uptake, resulting in abnormal hemoglobin synthesisCharacterized by the presence of ringed sideroblasts in the bone marrow – red cells containing iron granules that have not been synthesized into hemoglobin, but instead are arranged in a circle around the nucleus.
37Can be acquired or hereditary Acquired SA is the most common May be idiopathic or associated with other disordersReversible - secondary to alcoholism, drug reactions, copper deficiency and hypothermiaHereditary SA –rare, almost always in males – probably X-linked recessive gene.
38Clinical manifestations Along with cardiovascular and respiratory manifestations of anemia, may also show signs of iron overload (hemosiderosis)Enlargement of spleen and liverBronze tint to skinHeart rhythm disturbancesImpaired growth and development in young children
39Treatment Drug therapy – pyridoxine Iron overload requires repeated blood removal – phlebotomiesIron chelating agents in anemic individuals who require transfusions
40Normocytic –Normochromic Anemias RBC’s are normal in size and hemoglobin content, but are too few in number.Less common than the macrocytic and microcytic anemias
41Several types that do not have anything else in common: AplasticPosthemorrhagicHemolyticSickle cellAnemia of chronic inflammation
42Aplastic anemiaFortunately, this condition is rare; it means the RBC’s are not being produced. Bone marrow stem cells are not functioning.Can result from disorders of the bone marrow, such as cancer; autoimmune diseases; renal failure due to lack of erythropoietin; B12 or folate deficiency; congenital problems; or it may be induced by radiation, toxins or the use of some drugs, such as chloramphenicol.Treatment – treat the underlying disorder, blood transfusions, and possibly bone marrow transplant
43Posthemorrhagic Caused by sudden loss of blood. Can be fatal if loss exceeds % of plasma volume.Treatment is to restore blood volume by intravenous administration of saline, dextran, albumin, plasma or whole blood.
44Hemolytic Anemia Red blood cells are formed, but are broken down. May be acquired or hereditary.Acquired hemolytic anemia is extrinsic, due to factors outside the red blood cell, such as an abnormal autoimmune response that targets red cells, or by improper matches during transfusions; or due to infection, systemic diseases, or drugs or toxins.
45Hereditary or intrinsic hemolytic anemias: Sickle cell anemia – due to a change in one amino acid in each of the beta-chains in the globin, under conditions of low oxygen the hemoglobin forms insoluble threads that change the shape of the erythrocyte into a crescent. This shape is not as flexible and tend to be trapped in the capillaries, where they obstruct blood flow and cause ischemic injury.
46The life span of a sickled cell is only 20 days rather than 120, and is removed from circulation by the spleen.Either mechanism causes a chronic anemia.Sickle crisis: episodes of acute sickling that block blood flow, posing the threat of widespread and possibly life-threatening ischemic organ damage.
48This is an inheritable condition. If a person has only one defective gene, it is called sickle cell trait, and the person is essentially normal. This condition tends to persist because it protects against malaria. When a cell becomes infected by the parasite, the cell sickles and is removed from circulation, preventing reproduction of the parasite.Only when a person inherits two defective genes does sickle cell anemia occur.
49Thalassemia is another hemolytic disorder where the alpha or beta chains of the globin are defective, or the beta chain is not produced. When the beta protein is lacking, the alpha protein accumulates and causes destructive membrane effects, causing these cells to be rapidly removed from the circulation.Highest incidence in populations around the Mediterranean and Southeast Asia.Problem occurs when two defective genes are inherited; heterozygotes are essentially normal.
50Thalassemia major is an inherited form of hemolytic anemia, characterized by red blood cell (hemoglobin) production abnormalities. This is the most severe form of anemia, and the oxygen depletion in the body becomes apparent within the first 6 months of life. If left untreated, death usually results within a few years. Note the small, pale (hypochromic), abnormally-shaped red blood cells associated with thalassemia major.
51Myeloproliferative Disorders The opposite of anemias – here we have too many RBC’s.Polycythemia – excessive production of RBC’sPrimary polycythemia – cause is unknown, but is in effect, a benign tumor of the marrow, leading to increased numbers of stem cells and therefore RBC’s, and splenomegally.Polycythemia vera – rare, mostly Northern European Jewish males between 60 – 80 yrs.
52Secondary Polycythemia Due to the overproduction of erythropoietin caused by hypoxia. This is more common.Seen in:Persons living at high altitudesSmokersCOPD patientsCongestive heart failure patients
53Polcythemia leads to : Increased blood volume and viscosity Congestion of liver and spleenClottingThrombus formation(last two may be due increased numbers of platelets along with the increase in RBC’s due to bone marrow dysfunction.)
54Clinical manifestation of Polycythemia HeadacheDizzinessWeaknessIncreased blood pressureItching / sweating
55Treatment of polycythemia Reduce blood volume by phlebotomy – ml.Treat underlying condition - Stop smokingRadioactive phosphorus injectionsPrevent thrombosis